Ultrafine Pt Nanoparticles on Defective Tungsten Oxide for Photocatalytic Ethylene Synthesis

The selective conversion of ethane (C₂H₆) to ethylene (C₂H₄) under mild conditions is highly wanted, yet very challenging. Herein, it is demonstrated that a Pt/WO_3-x catalyst, constructed by supporting ultrafine Pt nanoparticles on the surface of oxygen-deficient tungsten oxide (WO_3-x) nanoplates, is efficient and reusable for photocatalytic C₂H₆ dehydrogenation to produce C₂H₄ with high selectivity. Specifically, under pure light irradiation, the optimized Pt/WO_3-x photocatalyst exhibits C₂H₄ and H₂ yield rates of 291.8 and 373.4 µmol g^-1 h^-1, respectively, coupled with a small formation of CO (85.2 µmol g^-1 h^-1) and CH₄ (19.0 µmol g^-1 h^-1), corresponding to a high C₂H₄ selectivity of 84.9%. Experimental and theoretical studies reveal that the vacancy-rich WO_3-x catalyst enables broad optical harvesting to generate charge carriers by light for working the redox reactions. Meanwhile, the Pt cocatalyst reinforces adsorption of C₂H₆, desorption of key reaction species, and separation and migration of light-induced charges to promote the dehydrogenation reaction with high productivity and selectivity. In situ diffuse reflectance infrared Fourier transform spectroscopy and density functional theory calculation expose the key intermediates formed on the Pt/WO_3-x catalyst during the reaction, which permits the construction of the possible C₂H₆ dehydrogenation mechanism.